rear derailleur adjustment on FS bike

Hi guys, just joined your forum and have enjoyed reading the threads.
Got a question for ya, how do u go about adjusting the rear derailleur on a full suspension bike. I have a Specialized FSR with XTR and have adjusted it as per
al the info I have read, however when I sit on the bike, the cable goes slack because of the rear suspension and shifting is horrendous. do I just take up the slack with the barrel adjustment?
I tried it and it seemed to work. Just wanted to know if this is the way to do this. Any help or opinions would be appreciated

The FSR's I've worked on were prone to ghost-shifting to lower gears as the suspension compressed... might be a good excuse to try a SRAM ESP rear-derailleur/shifter combo, if you like twist-shift. It takes twice as much cable travel to shift ESP, making it theoretically less-prone to ghost-shifting.

However, I can't think why the cable would have more slack when the suspension squats, instead of less slack (as was typical of the ones I worked with)... unless perhaps the cable housing that joins the front and rear frames is too short, and it can't quite bridge the gap between the two housing stops until the suspension squats and the stops move toward eachother. Do you happen to have any photos of your individual bike that you could post?

This image is a bit bigger than I would want to put into the thread, but visit http://www.specialized.com/SBCBikePo...20FSRxc%20Disc and look at the piece of rear derailleur housing that links the front and rear frames. Notice it arches up a touch. If yours is stretched taut when you're not on the bike, then you'd want to use a longer piece of housing.

so thats probably why this is happeniing.
the cable housing is a bit short due to the fact that I added an X-rated Link
to replace the old one. it recommended
I change out the housing because it might be too short, but I thought it was okay. so for it to work properly the cable should have a bit of a bend to it when I am not sitting on the bike. right now its perfectly straight. thanks for solving my problem, much appreciated.